The present invent relates generally to the field of envelope inserting machines, and more particularly to a novel collations feeding mechanism for feeding collations of varying thickness into envelopes.
Envelope inserting machines have long been well known, and a large variety of such machines are commercially available. In general, these machines store a batch of envelopes in a storage and feeding device, and feed envelopes seriatim to an inserting position at which packets of insert material, usually referred to as collations, are inserted into successive envelopes, the flaps thereof having been opened during movement from the storage device to the inserting position, and the throats of the envelopes having been opened when the envelopes reach the inserting position. After the envelopes have received the collations, which may be of varying thickness they are fed through devices which closed the envelope flaps and seal them, after which they are typically fed to a mailing machine which affixes appropriate postage to the envelopes and they are then stacked for further handling.
There are typically two different methods employed for inserting a collation into an envelope, one being a reciprocating pusher mechanism in which a pushing device engages the trailing edge of a collation and pushes it into an envelope held at an inserting position. The other method involves a rotary feeding mechanism, such as a plurality of opposed cooperating roller sets, opposed cooperating endless conveyor belts or one conveyor belt with an opposed cooperating back up roller, all of which run continuously in the same direction to feed successive collations along a feed path, at the end of which the collations are inserted into envelopes directly from the last cooperating roller set or the end of the conveyor belts or belt and last back up roller, as the case may be. Both systems are widely used and each has advantages and disadvantages, but generally speaking the reciprocating pusher mechanisms are utilized more in smaller, low to medium volume envelope inserting machines, while the rotary mechanisms are utilized more in large size high volume inserting machines. The reason for this is principally that this type of feeding mechanism is better suited to the high speed operation that is typically involved in the large high volume inserting machines. Generally speaking, these feeding mechanism work quite well, and both types have met with considerable commercial success in their respective preferred environments.
One serious drawback of the rotary mechanisms usually associated with high volume inserting machines is that the feeding mechanism is virtually incapable of inserting a single sheet, and with less frequency even two or possibly three sheets, of paper into an envelope due to the physical shape and size of the parts of the feeding device adjacent to the throat of the envelope. The reason for this that in the typical arrangements of these heretofore known rotary feeding mechanisms, the last roller set, or the end of the conveyor belts or belt and last back up roller, as the case may be, is spaced somewhat from the throat of the envelope disposed at the inserting position. Thus, depending on the specific shape of these parts, the collation is firmly gripped by the opposed roller sets or by the conveyor belts or belt and back up roller through its path of movement as it approaches the throat of an envelope, and even as the collation is partially inserted into the envelope. However, because the terminal parts of the rotary feeding mechanisms cannot physically reach into the open envelope, the grip thereof on the collation is released before the collation is fully inserted into the envelope, thereby leaving the collation to move further into the envelope under its own momentum.
It will be apparent that this is not a problem with the reciprocating pusher type collation feeding mechanisms, since the collation is literally pushed into the envelope until it is fully inserted therein and the leading edge of the collation is disposed at the bottom of the envelope. However, with regard to the rotary mechanisms, the loss of positive gripping contact between the feeding mechanism and the collation before the collation is fully inserted into the envelope presents a serious problem when the collation consists of only one sheet, and possibly two or three sheets, depending on the nature of the paper, because there is insufficient inertia in a single sheet, or in so few sheets, to maintain the momentum necessary to move the collation fully into the envelope. The collation stops with a small trailing edge portion thereof projecting above the crease line between the front surface and the flap of the envelope.
This typically causes any one or more of a number of problems. One is that when the envelope flap is closed during further movement of the envelope, it creates a short fold in the insert material, usually at an intermediate location on the sheet when it is opened, which fold is undesirable because it tends to destroy the otherwise neat appearance of previously folded sheets. Another problem is that the small trailing edge portion of the collation may be too thick to fold in response to the envelope flap being closed, in which case the flat may fold at some point other than the normal crease line between the flap and the front wall of the envelope. This results in a short flap, which will not properly engage the rear wall of the envelope, and may, during the sealing process, seal to the portion of the collation that is projecting above the rear wall of the envelope. This situation present obviously unacceptable results when the envelope is opened and an attempt is made to remove the insert. A still further problem is that either the short folded portion of the collation or the folded flap, as the case may be, may cause the envelope to jam, either in the ejection mechanism of the inserting machine or in other processing apparatus through which the envelope may be fed in the course of further processing, thereby causing down time while an operator clears the jammed envelope from the equipment. It will be apparent that all of these problems are unacceptable if an inserting machine is utilized to feed one or a just a few sheets with any degree of frequency and yet remain commercially viable.
Thus, there is a need for a continuously operating rotary feeding mechanism of the types above described which is capable of feeding collations consisting of either one or a very few number of sheets into envelopes with the same degree of consistent reliability as these mechanisms now feed collations consisting of many sheets of insert material.